Objective To explore expression changes of ProBDNF and its receptors P75NTR and Sortilin in Posterior horn of the spinal cord followed by Complete Freunds Adjuvant (CFA) induced inflammatory pain.Methods Rats received plantar subcutaneous injection of CFA and saline mixed solvent 100 μl, establishing inflammatory pain model.Rats were randomly divided into normal group, after injection of CFA 6 h, 1 d, 3 d, 7 d and 14 d groups.The change of paw withdrawal threshold (PWT) was observed by Von Frey fibers in rats at different time points; the expressions of ProBDNF, P75NTR and Sortilin in spinal dorsal horn were detected using immunohistochemistry.Results PWT decreased quickly at 1 h after CFA injection, and to the lowest value at 6 h.PWT gradually rose at 3 d and was still lower than baseline at 14 d.ProBDNF expression can be seen in the normal spinal dorsal horn.Compared with the contralateral side, ProBDNF was significantly increased in ispilateral spinal dorsal horn at 1 d after CFA injection; the increase continued until about 7 d, and gradually restored at 14 d.Normal rat spinal dorsal horn had a weak expression of P75NTR, mainly in the posterior horn Ⅰ, Ⅱ lamellar; P75NTR was significantly increased in the spinal dorsal horn of the injected side at 6h after CFA injection, positive products in Ⅲ-Ⅴ layers were also increased.This increase reached its peak at 7 d and gradually decreased at 14 d.Sortilin positive product was weak in the normal superficial spinal dorsal horn.Sortilin expression in the spinal dorsal horn had no significant difference at different time points after CFA injection.Conclusion CFA can induce inflammatory pain more than 2 weeks duration; ProBDNF and P75NTR upregulation in spinal dorsal horn may be related to peripheral pain signal transmission and central sensitization in inflammatory pain.